Year	billion cubic meters
1961	29
1962	29
1963	29
1964	29
1965	29
1966	29
1967	29
1968	29
1969	29
1970	29
1971	29
1972	29
1973	29
1974	29
1975	29
1976	29
1977	29
1978	29
1979	29
1980	29
1981	29
1982	29
1983	29
1984	29
1985	29
1986	29
1987	29
1988	29
1989	29
1990	29
1991	29
1992	29
1993	29
1994	29
1995	29
1996	29
1997	29
1998	29
1999	29
2000	29
2001	29
2002	29
2003	29
2004	29
2005	29
2006	29
2007	29
2008	29
2009	29
2010	29
2011	29
2012	29
2013	29
2014	29
2015	29
2016	29
2017	29
2018	29
2019	29
2020	29